An ink jet printer prints a picture upon a medium such as paper or the like by discharging minute liquid drops of ink from minute nozzle holes provided in an ink jet head, according to printing data. Some such printer devices using such an ink jet method are capable of making full color pictures with an ink jet head which is charged with inks of the four colors cyan, magenta, yellow, and black, or with inks of six colors by adding to those light cyan and light magenta.
Recently it has also become widespread, by installing such an ink jet head to a production device, to perform manufacture of wiring patterns and color filters and the like, and to apply such processes in industry.
FIG. 10 is a perspective view of a prior art ink jet head. FIG. 11 is a perspective view of a portion thereof cut along the line CC-CC in FIG. 10. And FIG. 12 is a perspective view showing the fitting state of a prior art multi color ink jet head to a head holding member.
A number of grooving processes are performed by dicing upon a piezoelectric substrate 101 which has been polarized in its thickness direction, and thereby ink chambers 104 are formed. Electrodes 105 are formed upon the inner walls of these ink chambers 104, and electrode protective layers (not shown in the drawings) of thickness of about 10 μm are formed so as to cover over these electrodes 105. Electrically conductive material not shown in the figures is loaded into the rear end portions of the electrodes 104. A common ink chamber 103 is formed in a cover member 102. This common ink chamber 103 is communicated with all the ink chambers upon the piezoelectric substrate 101, and thereby it is arranged to supply ink from this common ink chamber 103 to the various ink chambers 104. The ink jet head 100 consists of the piezoelectric substrate 101 with the cover member 102 adhered thereto.
In the structure described above, when voltages corresponding to the printing data are applied to the electrodes 105, the wall portions of these ink chambers 104 are deformed, and the ink within the ink chambers 104 is pressurized. As a result, this ink is discharged from nozzle holes, not shown in the figures, which are provided in front end portions of the ink chambers 104.
With this type of piezoelectric method, since it is possible to control the amount of pressurization of he ink and the volumes of the discharged ink drops by regulating the voltage, thus controlling the deformation of the piezoelectric elements, accordingly the distinguishing feature is that tone printing is available in a simple manner.
It is possible to perform color printing by providing a plurality of ink jet heads 100 of the structure described above in combination, and by outputting inks of different colors from the various heads. FIG. 12 shows an ink jet head 200 in which four ink jet heads 100 are disposed upon a head holding member 106, and which is capable of such color printing.
However, since these individual ink jet heads 100 are separate members, it is necessary to assemble these separate members to the head holding member 106, and it is not guaranteed that the positions of the various nozzle holes are determined at high accuracy, so that the problem has arisen of the yield factor being low.
Thus, in order to solve this problem, the construction disclosed in Patent Document #1 has been proposed.
That is, by forming an ink chamber of a different length for each of the ink colors, and by supplying inks of the various colors from ink supply conduits corresponding to these ink chambers of different lengths which are formed in a top plate, it becomes possible, by processing a single piezoelectric substrate, to manufacture an ink jet head which provides multi color printing in yellow, magenta, cyan, and black. According to this structure the beneficial effect is obtained that it is possible to enhance the quality of the printing, since it is possible to perform determination of the positions of the various nozzle holes at high accuracy without it being necessary to give any consideration to positional deviation between the different heads; and, moreover, the yield factor during mass production is enhanced.
Patent Document #1: JP H10-235907A